Telephone system



July 15, 1941. F. A. HUBBARD' TELEPHONE SYSTEM Filed June 21. 1940 4 Sheets-Sheet l lNl/ENTOR FRANCIS A. HUBBARD ATTORNEY July 15', '1 941.

F. A. HUBBARD TELEPHONESYSTEM Filed June 21, 1940 4 SheetsSheet 2 INVENTOR F RANC/S AHUBBARD ATTORNEY July 15, 1941. F; A. HUBBARD 2,248,995

' TELEPHONE SYSTEM Filed June 21, 1940 4 Sheets-Sheet' s INVENTOR By FRANCIS A. HUBBARD A Z'TORNEV y 5, 1941. F. A. HUBBARD- 2,248,995

TELEPHONE SYSTEM Filed June 21, 1940 4 Sheets-Sheet 4 MAR/(ER FIG. 4

/NVENTOR B FRANCIS A. HUBBARD ATTORNEY Patented July 15, 1941 OFFICE TELEPHONE SYSTEM Francis A. Hubbard, Maplewood, N. J., assignor to Bell Telephone Laboratories, New York, N. Y a corporation of Incorporated,

New York Application June 21, 1940,, Serial No. 341,628

12 Claims.

This invention relates to telephone'systems and particularly to systems in which automatic switches are used for establishing conversational connections,

The object of the invention is to simplify and otherwise to improve the mechanisms which receive and utilize the designations transmitted over telephone lines for the purpose of controlling the operation of the automatic switches.

It has been proposed heretofore 'to employ.al' ternating currents in combinations of different frequencies for sending called designations over a subscriber's line'to the central oflice and to record these designation signals on a magnetic tape in the central office sender as they are received from the line. The ofiice code portion of the designation is then reproduced from the tape, separated into the component frequencies by a selective signal receiver and utilized'to set the code digit registers. In systems employing mark ers this code registration is then transferred to a selected marker, which controls the operation of the switches of the preliminary switching stages. Thereupon the numerical portion of the designation is reproduced from the tape in the sender and transmitted over the extended connection to a terminating recording sender Whereit is received and used to complete the connection. A system of this kind is disclosed and claimed in the application of B, F. Lewis and H. A. Lewis, Serial No. 341,631, filed June 21,1940. In'such a system, however, it is necessary to provide each one of the originating senders with a selective signal receiver for setting the oifice code registers. Moreover,

an originating office having senders equipped with these magnetic recorders can extend calls only to other offices having senders also provided with alternating current signal receivers. P

It is, therefore, a feature of the present invention to realize economies and other advantages over these prior systems by eliminating the somewhat expensive signal receiver from all of the originating senders. This is accomplished by providing each of the markers, the number of which is small compared with the number of senders required, with a signal receiver, which receives the office code designation directly from the magneticmedium in the sender. More specifically, the oflice and numerical designations are received from the subscribers line in the form of alternating current signals and recorded on a magnetic tape or other medium. The sender is connected to a marker, and the ofiice code is transferred as alternating currentsignals from the tape to thefrequency selective receiver in the marker. Thereafter the numerical designation is reproduced from the magnetic tape and is sent as alternating signals over the extended connection to the terminating sender, provided this latter sender is equipped with a frequency selective receiver. 7 g 1 Some ofiices in the area may have switches which are controlled by revertive pulses, suchas paneltype switches. Others may be equipped with step-by-step switches which are operated by direct current impulses sent directlythereto. And it is, of course, desirable that calls should be completed to these oflices from the originating office as well as to offices equipped to receive the designations in the form of alternating current signals.

Accordingly another feature of the invention is a system in whichthe-originating oflicaabove described, is provided with a number of. common decoders, in addition to the recording senders and markers, which are used only on calls that are to be completed to offlces having switches re-' quiring direct current impulses either'directively or. revertively transmitted. -When the markerreceives the olfice code from the magnetic tapein the sender, it translates the code and sends class-- of-call information back to the sender. If this information indicates the called office is equipped to receive alternating current designation signals, these signals are immediately sent thereto from the magnetic j tape in the originating sender. However, if the called oficerequires direct current impulses, the sender seizes one'of the decoders, and the numerical designation on the tape is sent thereto in the: form of alternating current signals. A frequency selective receiver in the decoder translates these signals into register operations, and the registration thus established in the decoder is sent back to the sender where it is set upon transmitting registers in form suitable for controlling the switches or other mechanism in the called office. V I

Another feature of the invention is. an; arrangement'in which the magnetic tape in the sender is driven at a relatively high speed during the process of transferring the oifice code designation from the tape to the markerand at a 1'61,-

atively low speed duringjthe reproductionand transmission of the numerical designation..;'By driving the tape at high speed while theoflice code is being transferred, the holding time of the marker is materially. reduced. v

Thus the advantages 'of' alternating current signaling are realized in the transmission oftele phone designations, while 7 at i the same time the more expensive parts of the equipment necessary for receiving and translating these designations are located in the markers and decoders in order to reduce to a minimum the amount of such equipment required.

These and other features of the invention will be discussed more fully in the following detailed specification,

In the drawings accompanying the specification, Figs. 1 to 4, when arranged in the order illustrated in Fig. 5, disclose an automatic telephone system incorporating the features of this invention.

Fig. 1 shows a calling subscribers line appearing in a local central oifice and having access through automatic switches therein to local called subscribers lines. This figure also shows the switches and equipment in two distant ofiices of different classes;

Figs. 2 and 3 show a common recording sender in the local office; and

Fig. 4 shows a common switch-controlling marker, and a common decoder together with means for connecting them to the common recording senders.

The subscribers lines in the local oflice, including the line I00, appear in line switches LS. These line switches are joined to first or district selector switches S by means of link circuits or junctors IN. The district selectors S have access to oflice selectors S-I through interconnecting junctors, and the office selectors have access to trunks extending to the terminating equipment in the same ofiice and to outgoing trunks extending to the distant offices. For example, the local trunk I02 extends from the office selector S-I to the incoming selector S--2 in the same oflice, and the incoming selector together with the final selector S-3 serves to complete the connection to a local called line I03. The local incoming trunk I02 also has access through an incoming sender selector switch 8-4 to an incoming sender I04. The sender I04 in cooperation with the terminating markers (not shown) controls the operation of the incoming and final switches S-2 and S-3 for completing these connections.

The interoffice trunk I05 appearing in the oflice selector S-I extends to the distant ofiice I06 where it appears in an incoming selector S-5 which serves to further extend the connection through the final selector S-B to a called'line I01. The interofiice trunk I05 is also extended through the sender selector switch 8-1 to the incoming sender I00.

Although the invention is not so limited, it is assumed for the purpose of the present disclosure that the switches used in the originating ofiice and in the distant office I06 are of the cross-bar type-and that these switches are controlled'in their selective operations by means of common register senders and common switch-controlling markers.

The interoflice trunk I09, to which the oifice selector S-I also has access, extends to a distant ofiice II0 which is assumed to be equipped with switches of a different type, such as panel switches or step-by-step switches.

In the system disclosed it is assumed that the subscribers lines are arranged for the transmission of telephone designations in the form of alternating currents of different frequencies, each of the several digital characters of a designation being represented by a particular combination or code of frequencies. For example, if five different frequencies are employed, each digital character may be represented by a combination of two of the five frequencies. In order that these designation signals may be transmitted over the subscribers line to the central ofiice, the substation is equipped with a transmitter of any suitable type which the subscriber may manipulate to send the successive signals, two frequencies at a time, characterizing the wanted designation. A reed type of sender, such as the sender III located at the substation of line I00, is suitable for this purpose. A transmitter of this type is disclosed and described in R. F. Mallina Patent 2,147,710 of February 21, 1939.

At the local central omce the recording sender, shown in Figs. 2 and 3, is arranged to receive and record the alternating current signals transmitted over the subscribers line. The sender is automatically associated with the junctor IOI when the subscriber calls by means of the sender selector switch 8-8. The alternating current signals incoming from the sub-scribers line pass through the sender selector 8+8 and over the signaling circuit I I2 to the sender where theyare selected by a band-pass filter 20I. After passing through the filter 20I the signal currents are amplified by an amplifier 202 and delivered to the output circuit 203. Some of the energy from the amplifier 202 is applied to an enabling device 204. The enabler 204'serves to extend the output circuit 203 to the recording unit 30I of a magnetic recording mechanism 300. Generally speaking the function of the enabling device 204 is to respond to the incoming signals and to prepare a circuit at the proper time for delivering these signals to the recorder and to maintain the prepared circuit for the necessary period of time. Since the specific structure of the enabler is not necessary to an understanding of the present invention, it has been shown in diagrammatic form. For a complete description of the manner in which apparatus of this kind functions, reference may be had to the pending application of A. A. Lundstrom, Serial No. 306,4:66, filed No vember 28, 1939.

The magnetic recording mechanism of the sender includes a movablewire or tape 302, a substantial portion of which is normally stored in the container 303. At any suitable time following the seizure of the sender the driving motor 304 is started, and the feed mechanism 305 drives the tape in the direction indicated by the arrows, withdrawing it from the supply container 303 and advancing it through the recording unit 30 I to the second container 305. As the tape passes through the recording unit 30I it is magnetized in accordance with the incoming alternating current signals to record both the office and numerical designations, and the magnetized tape is then stored in the container 306.

After all or a substantial part of the designation is recorded on the tape 302, the sender seizes and connects itself to an idle switch-controlling marker 40I through a marker connector 402. As soon thereafter as the marker is ready, that section of the tape 302 on which the ofiice designation is recorded is withdrawn from the container 306 and driven through the reproducing units 301 and returned to the container 303. For this purpose a second feed mechanism 308 is provided and is driven through the clutch devices 309 and 3I0 by means of a driving motor3II. The driving motor 3 is started in operation by means: of a control relay 205 at any convenient time followingthe seizure of the sender. J The motor 3 is coupled to the feed mechanism 300 by means of a clutching device 309 constructed The tape 302 is driven at high speed through the reproducing unit 301, and alternating current signals, corresponding to those transmitted over the subscriber's line, representing the office code designation are transferred directly to the frequency selective receiving mechanism 403 in the marker. The circuit for this purpose extends from the reproducing unit 301 over conductors 3l5 through the back contacts of relay 3l3, conductors 3H5, through the connector 402 to the common input circuit 404 of the frequency selective filters 405, 406, 401, 408 and 409. These alternating current signals are selected by the filters, detected and amplified by the associated detector amplifiers 0, 4| l, M2, M3 and 4M, and are then utilized to cause the setting of the switch-controlling registers 4 l 5. When the oflice code has been transferred to the marker, the circuitfor the clutch device 309 is opened to discontinue the high speed movement of the tape. The reason for driving the tape at high speed is to conserve the holding time of the markenwhich is a relatively expensive mechanism.

At the proper time thereafter the low speed clutch device 3l0 is energized to clutch the motor shaft 3 l l to the drive shaft 3| 8 through gears 332 and 333. The tape 302 is driven atarelatively low speed to reproduce in the circuit 3l5 the alternating current signals representing the numerical designation of the called line. In the meantime the marker 40I has determined the destination of the call and has operated the switches S and Sl to extend the connection from the subscribers line over the trunk either to an ofiice arranged to receive alternating current designation signals or to an office equipped with means responsive to direct current impulses. If the called office is one that requires alternating current signals, the signal circuit 3|5 is extended directly through the switches S and S-l and over the selected trunk to the sender in the called oilice, such as the sender I04 in the local office or the sender 'l 08 in the distant ofiice. However, if the call is directed to an office requiring the transmission of direct current signals, the sender seizes an idle decoder 4H5 through a connector 4!! immediately after the marker 40l has received the ofiice code designation. Following the seizure of the decoder M0 the signal circuit 3! 5 is extended through the connector M1 to the frequency selective receiver 8 in the decoder. In this case the alternating current signals reproduced from the tape 302 are transmitted into the decoder where they are selected by the frequency selective receiver M8 and utilizedto operate the decoding registers 4 l 0. After the signals have been translated by the registers M9, this information is transferred back through the connector M1 to transmitting-registers 200 in the sender. Thereafter theisender-causes the numerical designation'to be transmitted over the extended connection to the distant oflice in the form of direct current impulses, eitherforward- 1y or revertively transmitted, in accordance with the settings of' the transmission registers 200.

It was noted above that the switches illustrated in the local ofiice and'in the distant oflice I06 are assumed to be of the cross-bartype. 'Since these switches are well known in the art it is not considered necessary to disclose them in detail. Likewise the common controllingsenders and the common markers are illustrated largely in diagrammatic'manner, many of their details being omitted for the sake of clearness. For a better understanding of the principles of the cross-bar system and the details of operation, reference is made to the following: Carpenter PatentNo. 2,089,921 of August 10, 1937; Carpenter Patent No. 2,093,117 of September 14, 1937; Carpenter application Serial No. 214,356, filed June 17, 1938.

Thedetailed operation of the system will now be described. When a call is initiated on one of the subscribers lines, such as line I00, the line switch LS and the sender selector switch 8-8 are operated to extend the calling line over the link or, junctor IM to the district selector S and also to the idle sender disclosed in Figs. 2 and 3. The seizure of the sender results in the establishment of a signaling and controlling circuit which may be traced from battery through the winding of control relay 201, conductor 208 through the sender selector S -8 thence through the line switch LS over the loop of the subscribers line and returning through the line switch and sender selector over conductor 209 to ground through the reactance coil 2|0. A tone current is applied to the calling linejin any well-known manner to notify the calling subscriber that an idle sender has been seized and that he may proceed to transmit the wanted designation. Also the seizure of the sender results in the operation of relay 2| l, and the motor 304 operates the tape feed'mechanism 305 to start the'movement of the tape 302.

The subscriber transmits the wanted design-ation by manipulating the reed transmitter III to send first the oifice code characters, usually three in number, and then the four successive characters representing the numerical designation of the called line.

are passed by the filter 201, amplified by the amplifier 202 and delivered to'the circuit 203; Each signal passing through the amplifier 202 isapplied to the enabling devicei204iwhich serves, to introduce a preliminary delay'between the arrival of a signal and the operation of the control relay 2l2. When the relay. '2l2 operates at the end of the delay period, relay'2l3 is energized,

7 At some convenient time following the seizure of the sender, the relay 205 is operated to close the circuit .of motor 3! l. Motor 3!! drives the shaft 3, but the clutches 300 and 310 are ,ineffective at this time, and thefeed mechanism 308remainsatrest r 1 1 1 Since the control relay 2l2 in-the enabler operates on each incoming designation signal, it may serve to operate azcounting circuit 2M to count the digital-charactersas they are received. -When a1l characters have been received The "alternating current signals representing these designation'characters ductor 2I5 to operate the connector start relay 420. Relay 420 operates the connector 402, and

the sender is connected to an idle marker 40I.

As'soon-as the marker is ready to receive the ofiice code designation, it closes a circuittraceable over conductor 42I through the connector 002, conductor 3I4, normal contacts of relay 3l3, contacts of relay 3I2 to the clutch 300. The clutch 309 connects the shaft 3I'I to the shaft 3I8, and the feed mechanism 308 drives the tape at a relatively high speed through the reproducer 301. As the magnetized section of the tape containing the record of the office designation passes through the rep-roducer 301 the alternating current signals recorded thereon are reproduced in the circuit 3I5 and transmitted thereover through the contacts of relay 3l3, circuit 3I0 through the connector 402 to the input circuit 404. These alternating current signals are selected according to frequency by the filters of the receiver 403 and, after being detected and amplified, are used to set the register mechanism 4I5. signals are recorded on the tape 302 at one speed and reproduced therefrom at a higher speed, the frequencies of the reproduced signals are increased .by amounts depending upon the speed ratio. In otherwords, the frequencies of the signals applied to the receiver 403 in the marker are greater than the frequencies of the corresponding signals transmitted from the sub- Since the alternating current scribers station and recorded on the tape 302.

Accordingly the filters 405, 400, 401, 408 and 409 in the receiver 403 are designed to accommodate the signals of increased frequency values. In the well-known manner the marker makes use of the record established on the registers 4I5 to control the selective operation of the district and office switches S and S-I to extend the connection from; the subscribers line to the terminating equipment of the called office. At the same time the marker decodes the information it has received from the recorder 300 and transmits information back to thesender concerning the class of the call. This class information is transmitted over theconductors 422 through the connector 402 thence over conductors 423 to the class relays 2I0, 2II and 2I8. Following the receipt of the ofiice code signals, the marker also closes a circuit over conductor 424 through the connector 402, conductor 425 through the winding of relay 3l3 and a contact of operated relay 3I9 to battery. Relay 3l3 operates and locks over'control conductor 320. The function of relay 3l3 is to disconnect the reproducer'l from the circuit 3I6 extending to the marker and to connect the reproducer to the signal transmission circuit 32I. Relay 3I3 in operating also opens the circuit for the high. speed clutch 309, and the tape feed mechanism 308 comes to rest.

Assume first that the calling subscriber has transmitted the office name and number of the subscribers line I03 which appears in the same office with the line I00. Therefore, the marker 4M controls the district and ofiice switches as above explained to seize an idle trunk I02 extending to the incoming selector 8-2 in the Also the marker sends a class indication back to the sender to inform the sender that the calledline is in an office equipped with senders which receive the numerical designation in the form of alternating current signals,-.the same as those already recorded on the tape 302. This class information is established in the sender byoperating a class relay such as thetrelay 2I6. As soon as the complete numerical record has been received and recorded on the tape 302 the counting relay 2I9 is operated, and a circuit is completed from ground over the contact of relay 2I9 through the normal contact of control relay 220, conductor22l to the armature of control relay 322. When the sender is in condition to transmit the numerical record from the recorder 300 to the incoming sender I04, relay 322 is operatedand the circuit over conductor 22I is completed to the clutch mechanism 3). The feed device 308 is now driven at a relatively low speed; and the tape 302 is drawn through the reproducer 301 to reproduce the signals representing the numerical designation. These alternating current signals are transmitted over the circuit 3I5 through the front contacts of relay 3l3, circuit 32I, normal contacts of relay 324, circuit 325 through the normal contacts of relay 224, circuit 225, thence through the sender selector- S8 and through the district and office switches S and .S-I over the trunk I02 through sender selector S-4- to the frequency selective receiver H3 in the incoming sender I04. These-signals arerselected and utilized to operate the registers H4 in the sender I04, and the sender associates itself with an idle marker for the purpose of controlling the selective operation of the incoming and final switches S2 and S-3 to complete the-connection through to the called line I03.

As soon as the marker 40I and the sender of Figs. 2 and 3 have completed their functions they release. Similarly the terminating sender I04 and the terminating, marker, not shown, release after they have completed their functions. After the signals have been all reproduced from the tape 302 the feed mechanism 308 may continue to operate the tape until the proper amount, is restored to the storage container 303 ready for the next use. The magnetized areas of the tape are restored to their neutral condition by means of a magnetic eraser 328 through which the tape is driven before it reaches the recorder 30I. 7

Assume next that the designation transmitted by the subscriber of line I00 and recorded on the tape recorder 3V00pertains to the distant ofiice I06 and to the called line I01. In this case the marker 40I controls the district and oflice switches S and SP-I to extend the connection from the calling line over the inte'rofiice trunk I05 to the incoming selector S-5. Seizure of the trunk I05 causes the operation of sender selector S'I, and the trunk is extended to an idle sender I08 in the oflice I00. The class information received in the originating sender from the marker 40! indicates the class of the called office I00, and the sender prepares to reproduce and transmit the alternating current signals representing the number of the called 'lineto the distant ofiice. The transmission path of" relay 224, circuit 225 thence through the sender selector S8 and selector switches S and .S-l over trunk I through sender selector S to theinput circuit H5 of the frequency selective receiver H6 in the sender I08. These signals are decoded and recorded on the registers -I I1 and the sender I08, in conjunction with a terminating marker (not shown) serves to control the switches S'-5 and S6 to complete the connection to the called line I01. As before, the senders and markers are released as soon as they have completed their function.

Assume finally that the designation transmitted from the calling line I00 and recorded on the tape recorder 300 pertains to the distant ofiice H0 and to the called line H8 therein. The marker 40!, having received the ofiice code designation identifying the office H0, controls the district and ofiice switches S and Sl to extend the calling line I00 over the interoflice trunk I09 to the incoming selector switch S9 in the called ofice. In this case the class of the calledoflice H0 is identified in the sender in the originating ofiice by operating the class relay 218. The circuit for operating this relay extends from the marker 40! over conductor 426 through the connector 402, conductor 42! through the winding of relay 218 to battery. The operation of relay 2l8 is a signal to the sender that the called office is one that requires direct current impulses and is not equipped to receive the alternating current signals recorded on the tape 302. Therefore, the sender seizes 'an idle decoder 4H3. The seizure of the decoder M6 is effected by a circuit closed from ground through the contact of relay 218 through the winding of relay 428 to battery. Relay 428 causes the operation of connector 4|? to associate the sender with an idle decoder 4l6. Relay 2l8 also closes an obvious circuit for operating the switching relay 324. The numerical designation of the called line, which is recorded on the tape 302 in the form of alternating current signals, is now transferred to the decoder M6. The path over which the alternating current signals are transmitted fextends from the reproducer 301 over circuit 3I5,

front contacts of relay 3|3, circuit 32l, front contacts of relay 324, circuit 222 through the connector 4|! to the input circuit 429 of the frequency selective receiver M8 in the decoder.

The alternating current signals are selected by the receiver 8 and utilized to operate the decoding registers 4l9, and the registers M9 in turn cause the operation of transmission registers 206 in' they sender. The decoded information is transferred from the registers M9 to the registers 206 over a group of conductors 430 through the connector 4|! and over conductors 223.

In order to save holding time for the decoder 4l6 while the numerical designation signals are being transferred from the tape to said decoder, the tape feed mechanism 308 may be driven at high speed by energizing the high speed clutch 309 over a circuit to ground in any suitable manner by way of conductor 335.

As soon as the sender is ready to control the switches in the distant oflice H0 the relay 224 is operated under control of the transmission register circuit 206, and the called line designation is transmitted by impulse series in accordance with the setting of the registers 206. The transmission path extends over circuit 226 through the front contacts of relay 224, circuit 225,

' through the sender selector S8 and switches S and S--I over trunk I09 to the incoming selector switches of the step-by-step type,the designation; impulses are transmitted directly fromthe register mechanism 206. If, however, the selectors S9 and Sl0 are of the panel type, these impulses are transmitted revertively. In any event the selector 8-!) is first operated under the control ofythese designation impulses, and thereafter the final selector Sl 0 is operated to complete theconnection to the called subscribers line H8. As in the previous discussion, the marker l, is released as soon as it completes its functions. Also the decoder M6 is released as soon as it has decoded the numerical designation and transferred the necessary information back to the sender. Similarly the sender in the originating office is restored to its normal condition as soon as the switches in the distant ofiice have been operated and the connection completed.

In some cases-it may be desirable to equip the terminating office with a sender and a decoder for converting the called line designation from alternating current signal codes to direct current signals. This would make it unnecessary to provide decoders M6 at the originating office, and in such a case the originating ofiice sender would transfer the called lin-e designation to the called office in alternating current signals for all types of calls.

What is claimed is:

1. In a telephone system, a central office, a

line terminating in said central office, means for transmitting .over said line signal currents representing a telephone designation, automatic switches in said office, a recording sender in said office including amagnetizable medium, means responsive to said signal currents for magnetizing said medium to record the nation thereon, a switch-controlling marker, means for connecting said sender to 'said marker, means for reproducing the designation signal currents from said medium and transferring them directly into said marker, registers in said marker, and a signal receiving mechanism. in said marker responsive to the signals transferred from said medium for variably operating said registers to register saidtelephone designation in said marker, said markerserving to control the selective operation of said automatic switches in accordance with the registered designation.

2. Ina telephone system, a central office, a line terminating'in said ofiice, means for transmitting over said line'alternating current signals of different frequencies representing a telephonedesignation, automatic switches in said ofiice, a'recording sender in said oflice including I a movable magnetic medium, means responsive S 9. If the selectors S9 and S l0'are to said signals for magnetizing said medium to record the telephone designation thereon, a switch-controlling marker, means for connecting said marker to said sender, means for reproducing the alternating current signals recorded on said medium and for transferring them directly into said marker, a frequency selective receiving mechanism in said marker responsive to said signals, and registers in, saidmarker controlled by said. receiving mechanism for registering said telephone designation in the marker, said marker serving to control the selective operation of said automatic switches in accordance with the registered designation.

3. In a telephone system, a central office, a subscriber's line terminating in said office, means at the substation of said line for transmitting alternating signal currents in codes of different telephone designetic tape, means responsive to a call on said line for seizing an idleone of said senders, means responsive to said signal currents for magnetizing the tape of the seized sender to record said 'signal currents thereon, a plurality of switchcontrolling markers, means controlled by the A, I sender associated with said line for seizing and'lo markersanda plurality of common =decoders in making connection with an idle one of said markers, means for transferring the recorded signals from said movable tape directly into the seized marker, and means in the marker responsive to I said signals for registering the telephone desig l nation represented by said signals, said marker serving to control the selective operation of said switches.

4. In a telephone system, a central office, a

5 said calling line alternating current signals representing the officeandnumerical'desig'nations ofa called line, means responsive to said signals -for magnetizing said medium to record said designations on said medium, a plurality of common said-originating-office, means for connecting said sender to one of said markers, means for transferring to the marker the office designation signals'recorded on said 'medium, means in the marker'ior utilizing said signals to operate said switches to seize a trunk to the called office, means for connecting said sender to one of said decoders and for transferring to the decoder the signals on said medium representing the numerline terminating therein, a trunk, automaticg0 ical designatiommeans in the decoder for decodswitches in said office having access to said trunk, a recording sender in said ofiice including a magnetizable medium, means for transmitting over said line signals in codes of different frequencies -ing said signals and for sending the decoded information back to the sender, registers in the sender for receiving and registering said decoded information, switching means in the called ofiice,

representing a telephone designation, means reand means for sending direct current signals over reproducing from said medium the code signals representing a portion of said telephone designation and for transferring said code signals directly to said marker, means in the marker for decoding said signals and for registering therein the designation represented by said signals, said 8, a ecording sender in said callin Office marker serving to control said automatic switches to extend the connection over said trunk, and means for reproducing from said mediumcode signals representing the remainder of said telethe trunk between the originating and called offices to control the operation of said switching means in accordance with the setting of the registers in said sender.

7. In a telephone system, a calling office having automatic switches therein, a calling telephone line terminating in said ofiice, other ofiices having called lines terminating therein, trunks extending from said calling office to said other having a magnetizable medium therein, means for sending over said calling line alternating current signals representing the office and numerical designations of a called line, means responphone designation and for transmitting said Sig-"40 sive-to said signals for magnetizing said medium,

nals over said trunk.

5. In a telephone system, a calling office, a subscribers line terminating therein, a called oilice, automatic switches in said callingoifice a switch-controlling marker and a decoder in said calling oflice, means for connecting said sender to said marker, means for transferring to the marker the office designation signals recorded a trunk interconnecting said offices, means for '45 on said medium, means in the marker for utiliztransmitting over said line signals in codes of different frequencies representing the office code and numerical portions of a telephone designation, a recording sender in said calling office ining said signals to operate said switches to seize a-trunk to thecalled office, means for sending from the marker to the sender information con-' cerning the class of the called office, means decluding a movable magnetic tape, means 'resp0n- '50 pending on the class of the called oflice for consive'to said signals for magnetizing said tape to record them thereon, a switch-controlling marker, means for .connecting said sender to said marker, means for reproducing the code signals representing the office code portion of said designation and for transmitting said signals directly to said marker, means in the marker for decoding said signals and for registering the ofiice code designation therein, said marker serving to connecting said sender to said decoder and for transferring to the decoder the signals on said medium representing the numerical designation, means in the decoder for decoding said signals and for sending the decoded information to said sender,

registers in said sender for receiving and registering said decoded information, switching means in the called ofilce, and means for sending direct current signals over the trunk between the calltrol the automatic switches in said calling oifice" g and called Ofiices Control the p o of to extend a connection over said trunk to said called office, a recording sender in said called o'flice, means for reproducing from said magnetic tape the code signals representing the nu-,

said switching means in accordance with the setting of the registers of said sender.

8. In a telephone system a calling office havingautomatic switches therein, two other offices merical portion of said telephone designation and of diffe ent C s telephone line terminating for transmitting said signals over said trunk to said called ofiice, frequency selective means in the sender at said called office for decoding said signals and for registering the numerical designain said calling ofiice, trunks interconnecting said calling ofiice and said other offices, a recording sender in said calling ofiice having a magnetic tape therein, m-eans'for sending over said line tion therein, and automatic switches in said 7 .alternating'current signals in codes of different called ofiice controlled by said last-mentioned sender for further extending said connection.

26.,In a telephone system, an originating oifice having automatic switches therein, ,a, calling telefrequencies representing the .ofiice and numerical designations of a called line, means responsive.to'said signals-for magnetizing said tape, a plurality of.common markers and a plurality of phone line terminating in said oflice, called ofcommon "decoders in said calling oflice, means for connecting said sender to one of said markers, means for transferring to the marker the office designation signals recorded on said tape, means in the marker for utilizing said signals to operate said switches to seize a trunk to either of said other offices as a called office, means for sending from the marker to the sender information concerning the class of the called office, means effective if the class information transmitted to the sender indicates the call is for a particular one of said other offices for reproducing from said magnetic tape and sending over the trunk to said called office the alternating current signals representing the numerical designation, frequency selective means in said particular called oflice responsive to said alternating current signals, automatic switches in said particular called ofiice controlled by said frequency selective means for further extending the connection, means efiective if the class information indicates the call is for the other one of said called ofiices for connecting the sender to an idle decoder and for transferring to said decoder the alter nating current signals on said magnetic tape representing said numerical designation, means in the decoder responsive to said signals for decoding them and transferring the decoded information back to said sender, means in the sender for registering the decoded information received from said decoder, automatic switches in said other called ofilce, and means for sending direct current signals over said trunk to said other called ofi'ice to control the automatic switches therein in accordance with the information registered in said sender.

9. In a telephone system, a telephone line, a recording device including a movable magnetizable medium, means for transmitting over said line signal currents representing a telephone designation, means responsive to said signal currents for magnetizing said medium to record the designation thereon, means for reproducing from said medium a portion of the recorded designation, means for driving said medium at a given speed during the reproduction of said portion of the designation, means for reproducing the remainder of the designation recorded on said medium, and means for driving the medium at a different speed during the reproduction of said remainder of the designation.

10. In a telephone system, a telephone line, a recording mechanism including a movable magnetic medium, means for transmitting over said line signal currents representing the ofiice code and numerical designations of a called line, means responsive to said signal currents for magnetizing said medium to record said designations thereon, means for driving said medium at high speed, means eifective while said medium is moving at high speed for reproducing the signal currents representing said ofiice code designation, means for subsequently driving said medium at low speed, and means effective while said medium is moving at low speed for reproducing th signal currents representing said numerical designation.

11. In a telephone system, a telephone line, a recording mechanism including a movable mag- V netic tape, means for sending over said line ourrents representing the omce code and numerical designations of a called line, means responsive to said currents for magnetizing said tape to record said designations thereon, means for driving said tape at a uniform speed during the recording of said office and numerical designations, means for driving at high speed the section of said tape on which said ofiice code designation is recorded, means responsive to the movement of said section of the tape for reproducing said oifice code designation,-means for driving at low speedthe section of the tape on which said numerical designation is recorded, and means responsive to the movement of said last-mentioned section of said tape for reproducing said numerical designation.

12. In a telephone system, a subscriber's line, a recording mechanism including a movable magnetic tape, means at the subscribers station for transmitting over said line current signals representing the ofiice code and numerical designation of a called subsoribers line, means for driving an unmagnetized section of said tape at a uniform speed, means responsive to said signals for magnetizing the moving section of said tape to record thereonsaid ofiice and numerical designations, means for driving said tape at high speed to reproduce the signals representing the oflice code designation, means for registering the reproduced ofiice code designation, means for driving said tape at relatively low speed for reproducing the signals representing the numerical designation, and automatic switches controlled in accordance with the registered oifice designation for extending a telephone connection.

FRANCIS A. HUBBARD. 

